Silver sulfide nanoparticle assembly obtained by reacting an assembled silver nanoparticletemplate with hydrogen sulfide gas

Abstract

A fast, simple procedure is described for obtaining an assembly of silver sulfide nanoparticles(Ag2S NPs) on a glass substrate through reaction of a template of anassembled layer of silver nanoparticles (Ag NPs) with hydrogen sulfide(H2S) gas. The Ag NP template was prepared by assembling a monolayer of spherical Ag NPs(mean diameter of 7.4 nm) on a polyethylenimine-treated glass substrate. Exposure to pureH2S for 10 min converted the Ag NPs of the template toAg2S NPs. Theresulting Ag2S NP assembly, which retains the template nanostructure and particle distribution,was characterized by optical absorption spectroscopy, atomic force microscopy,transmission electron microscopy (TEM), scanning high resolution TEM, energydispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. TheAg2S NPs have a crystal structure of monoclinic acanthite, and while they retainedthe spherical shape of the original Ag NPs, their mean particle size increased to8.4 nm due to changes to the crystal structure when the Ag NPs are converted intoAg2S NPs. The measured optical absorption edge of theAg2S NP assembly indicated an indirect interband transition with a band gap energy of 1.71 eV. TheAg2S NP assembly absorbed light with wavelengths below 725 nm, and the absorbance increasedmonotonically toward the UV region.